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E39 (1997 - 2003) The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

I am really not so sure what all this fuss is about.
They are both interchangeable. It really does not matter which one you have. If you want to switch from mechanical to hydraulic or vice-versa, you can do it with no ill effects.
One is more expensive than the other one. Also, a few people experienced better service with the hydraulic type. Other experienced better service with the mechanical one. BMW "recommends" the hydraulic one. Pick one and be done with it.

I am really not so sure what all this fuss is about.
They are both interchangeable. It really does not matter which one you have. If you want to switch from mechanical to hydraulic or vice-versa, you can do it with no ill effects.
One is more expensive than the other one. Also, a few people experienced better service with the hydraulic type. Other experienced better service with the mechanical one. BMW "recommends" the hydraulic one. Pick one and be done with it.

the 'fuss' is over ordering the parts. you have to figure which you have before you order, or do like Rjim and buy both and return the unused one, but thats $10 or so in return shipping...

what I find silly is the BMW dealer can't tell you what was put on via your VIN, thats like a hospital (that you visit often) not having your blood type on file, especially here and now in the computer age.

Right, but again, if you had an hydraulic tensioner and you ordered a mechanical, you can replace it no problems. And vice-versa. You might be baffled when you take off the tensioner and it does not look like the original one you had, but it fits and works.
Probably that;s why BMW did not payed such attention to this detail, and maybe that's why you have same model/year cars with different setups, and not recognizable by VIN.
It's not such a dramatic part that will fubar your system if switch them (like for instance you pick a 90A instead of a 120A or 140A alternator). It's almost like changing tires - Michelin vs Dunlop or similar.

As doru is saying, it does not matter which one you get as they both bolt on the same way. So if you had mechanical and buy hydraulic, or vice versa....it will still work. It is just a matter of what you want to believe. some like the simplicity of mechanical and go with them, and some, including BMW recommend the hydraulic. mechanical are also a bit cheaper than the hydraulic if price is a concern.

I dunno about the "just pick one" approach either. I had recently taken my moms hydraulic AC tensioner off and attempted to put a mechanical AC tensioner in it's place. I wanted to change it since her tensioner was broken and I had a spare mechanical tensioner. Was not happening. It would not bolt up. You can retrofit a hydraulic onto a mechanical car with the right parts, but not the other way around in my trials and errors. The bracket that holds the AC compressor and tensioner to the car is different.

I ended up having to order the base for the hydraulic AC tensioner to fix her AC, which retails over 100 bucks. Hopefully I can salvage the rest of her old hydraulic parts onto the new base when it arrives and get her AC working. It's getting warm during the days! The base I had to order looks identical to this: http://www.bimmerfest.com/forums/sho...4&postcount=14

Thanks Mark, and you very well may be correct. I must admit, I did not do the work when done on my car, but according to the indie that did do it, I was told either one would bolt up. Now if that entails a little modification to get the mechanical to fit when you originally had the hydraulic...i cannot say for certain.

I dunno about the "just pick one" approach either. I had recently taken my moms hydraulic AC tensioner off and attempted to put a mechanical AC tensioner in it's place. I wanted to change it since her tensioner was broken and I had a spare mechanical tensioner. Was not happening. It would not bolt up. You can retrofit a hydraulic onto a mechanical car with the right parts, but not the other way around in my trials and errors. The bracket that holds the AC compressor and tensioner to the car is different.

I ended up having to order the base for the hydraulic AC tensioner to fix her AC, which retails over 100 bucks. Hopefully I can salvage the rest of her old hydraulic parts onto the new base when it arrives and get her AC working. It's getting warm during the days! The base I had to order looks identical to this: http://www.bimmerfest.com/forums/sho...4&postcount=14

Very good point. Thought they are retrofittable both ways. As it turns out you can retrofit only the "expensive" way. Hmmm....

Wow. This is a little like a spy looking at grainy pictures of satellite photos; you have to know exactly what to look for.

With a mirror and flashlight, at high noon, looking down on the engine, I was able to see the two upper pulleys (or rollers or whatever they are), both of which had the ribbed serpentine belt on them backward (i.e., ribs outward) and one of which had an off-center bolt on its face.

Buried in between the belt going in and out of those two pulleys, I noticed in the mirror a dime-sized raised outside hex casting with a hole in the center.

Am I correct in these two assumptions:
ASSUMPTION: The pulley with the off-center bolt is the idler pulley?
ASSUMPTION: The raised dime-sized hollow hex casting indicates a mechanical tensioner?

Taking your advice to get a mechanic's mirror, looking down from the top at high noon with a flashlight, today I determined I have a mechanical upper tensioner (now that I know what to look for) on my serpentine belt.

We have a complete Belt Tensioner section with everything need to complete your drive belt service.

Hi Joe,

At your links I saw a few interesting things (can you confirm or clarify)?
- The hydraulic tensioners appear to come in three separate parts
- The hydraulic tensioners appear to be different for each belt
- However, the mechanical tensioners appear to be the same for both belts

Since I've never done this job before, I'm hesitant to replace stuff I don't have to but it seems like a good practice to consider replacing any component that MUST be removed anyway (in my situation, I have a noise and I will replace the belts and anything else that needs replacing).

Do you have such a list of components that have to be removed anyway (to replace the belts)?
If so, that's the first list of things I'll consider ordering from you.

Lastly, I noticed you helpfully offer "genuine BMW", "OE", and branded parts (at various prices); can you tell me your customer-satisfaction experience with them (I tend to go with the lowest price unless that's shown to be folly otherwise, either because of fit complications or quality of results).

Sorry for so many questions but everyone else here is different in that they just seem to exude confidence in knowing how to make these decisions; but I don't have a clue and therefore need a lot of advice ... (the good news is when I'm done, I can provide the advice from that experience to others like me so answering the questions will help more than just me).

EAC will beat any published price on OEM parts from our competitors, that is really all you need to know. Find what you want, find who has it cheapest and give me a call,PM or email.

Changing these tensioners is very straight forward and it's a "once you get started you'll be fine" kind of job. There are not really any additional parts you need or anything, it would be a great time to put some fresh belts and idler/tensioner pullies in if you want.

At your links I saw a few interesting things (can you confirm or clarify)?
- The hydraulic tensioners appear to come in three separate parts
- The hydraulic tensioners appear to be different for each belt
- However, the mechanical tensioners appear to be the same for both belts

Since I've never done this job before, I'm hesitant to replace stuff I don't have to but it seems like a good practice to consider replacing any component that MUST be removed anyway (in my situation, I have a noise and I will replace the belts and anything else that needs replacing).

Do you have such a list of components that have to be removed anyway (to replace the belts)?
If so, that's the first list of things I'll consider ordering from you.

Lastly, I noticed you helpfully offer "genuine BMW", "OE", and branded parts (at various prices); can you tell me your customer-satisfaction experience with them (I tend to go with the lowest price unless that's shown to be folly otherwise, either because of fit complications or quality of results).

Sorry for so many questions but everyone else here is different in that they just seem to exude confidence in knowing how to make these decisions; but I don't have a clue and therefore need a lot of advice ... (the good news is when I'm done, I can provide the advice from that experience to others like me so answering the questions will help more than just me).

Thanks,
Blue

Yes, these are in three separate pieces. However the bracket and dampener are joined together.

The belts are all the same other then being build date specific.

We would also suggest replacing the idler pulley at the same time. You will already be in there and they usually go bad at the same time.

A note on belts... BMW use's Contential belts from the factory. They even say Contential on them from the factory.

So if your looking to save, go with the Contential belts.

In regards to our Genuine BMW parts and OEM Equivalents, I have personally used both and find that 9/10 the OEM Equivalents are just as good if not better (ie. Meyle HD) then the Genuine BMW parts!

Please feel free to shoot a PM if there is ever anything I can do for you!

While doing my research on the tools to prepare for replacing the belts and tensioners and rollers and pulleys and a concomitant cooling system overhaul, I found BETTER drawings in the Bentleys (on page 020-19) of the hydraulic tensioners and (on page 117-26) of the mechanical tensioners.\

Just completed a cooling system overhaul on my 530. New water pump, thermostat, radiator, radiator hoses, expansion tank, hose from radiator to expansion tank, both mechanical tensioners, WP pulley, temp sensor in lower hose, and the idler pulley. At 96K miles and all the bearings in the pulleys were dry with one being a tiny bit rusty with some loose debris. It was time to replace them. While I was at it, Fudman made a case to replace the vanos seals at the same time. Difficult to turn down when he offered up the seals since he has an extra set. He supplied me with a color photographed notebook of the Besian procedure which was invaluable. Turn the page, go to the next step. The vanos was easier than getting the radiator to fit back into place.

I bought original equipment supplier parts and I noted in many cases the OEM BMW parts I removed were from the same vendor as the new parts. All went well with one minor leak. I had difficulty getting the small hose from the radiator to the expansion tank barbed nipple to seal properly. The right clamp is the OEM style clamp. I tried to use a fuel line clamp on the expansion tank side and it would not fit due to clearance issues. I ended up with those crappy worm screw clamps and despite being tight, it was not tight enough.

As for bleeding the cooling system, my 530 has an axillary electric water pump. By placing the fan on low, temp on high, it turns on with the key (do not start engine) It forces out all the air when running and you need to keep adding coolant when it is running. I then opened the bleed screws with the pump running for a final purge of air. Started engine, waited 15 seconds, rev'd to 4K RPM 3 times and checked level. Did not change.

Summary of this thread:
I. There is no way to tell other than looking whether you have mechanical or hydraulic tensioners (or both).
II. Personally, I'd replace hydraulic with hydraulic; mechanical with mechanical (both work just fine).
III. The so-called hydraulic isn't hydraulic anyway - it's a spring encased in oil (according to cn90 I think).
IV. For my mechanical tensioners, the pulley is a T50 Torx (but it's never needed since the pulleys are not sold separately for mechanical tensioners).
V. To adjust the mechanical tensioner, use a 16mm socket on the raised molded nut on the body.
VI. To remove the mechanical tensioner, use a 13mm socket to remove the two bolts on the sides.
VII. The pulleys are sold separately with the hydraulic tensioners (which are more complex than mechanical).
VIII. You need a 5mm or 3/16" allen wrench to hold the AC mechanical tensioner in place to remove & replace.
IV. Instructions for removing all the drive belt system components are here.

I just realized, from this thread today, WHY everyone said to twist the centerbolt of my (mechanical) tensioners ... while I just could not fathom exactly what that would have gained me.

Now I know ...

Apparently ... FOR MECHANICAL TENSIONERS:
- There is never a need to turn the T50 Torx centerbolt ... because ...
a) The pulley isn't sold separately ... and ...
b) That's not how you release tension on the belts
(You use the 16mm boss molded into the body to release tension.)

However ... FOR HYDRAULIC TENSIONERS:
- Apparently you DO need to turn the centerbolt ... because ...
a) The pulley is not sold with the tensioner ... and ...
b) Apparently that's how you release the belt tension.

Bluebee: There is one more option (since you like to be complete ). With some of the aftermarket mechanical tensioners like the one I got from NAPA you have to wrench on the bolt in the center of the pulley.

Oh my! Yes indeed. I will update the list of parts to indicate the warning about non-OEM tensioners. Your picture shows the problem quite clearly (I wish everyone posted a picture with their answers).

Again, in that thread you referenced, I see cn90 saying that turning the centerbolt (in the middle of the pulley) on both mechanical and hydraulic tensioners releases tension on the belt; but I can't for the life of me, fathom why you'd do that with the OEM (INA brand) mechanical tensioners.

I wouldn't necessary classify it as a problem, just a different style. Fit and functionality are fine. I know some here are probably interested in keeping there vehicles as close to 100% original as possible, while others are interested some mix of price, availability, and quality. I was just pointing out the difference. Whether it is important or not is up to the individual. I have about 7000 miles on the one I put in, and no complaints or issues.

Hall I have 1997 bmw 318 ti and have problem for the head my car dos't have heat and I change ternotart still no heat and I have other problem when I drive my same time when I stop, stop ligh and I go the same thing holding I change oll raoters and still I have that problem sow please if you have any solotion please let me what i have to do
thank you